A cylinder with a height of 6.28 decimeters, its side area expansion is just a square, how many square decimeters is its surface area? Make it clear,

A cylinder with a height of 6.28 decimeters, its side area expansion is just a square, how many square decimeters is its surface area? Make it clear,


Side length * side length plus area of 2 circles
6.28 * 6.28 = 39.44 keep 2 decimal places, this is the side area
Because the circumference of the circle is also 6.28, the diameter = 6.28 / 3.14 = 2
The square of the area R of a circle is 1 * 3.14, because there are two circles with * 2 = 6.28
The result is 6.28 + 39.44 = 45.72 square decimeters



The side view of a cylinder is a square with an area of 16 π square. What is the radius of the bottom of the cylinder?


16π=4π×4π4π÷(2π)=2



A rectangular sheet of iron is 12.56 decimeters long and 6.28 decimeters wide. If you circle it into a cylinder, what is the volume of the cylinder? Use two pieces of iron
A rectangular sheet of iron is 12.56 decimeters long and 6.28 decimeters wide. If it is enclosed into a cylinder, what is the volume of the cylinder? (use two different methods and calculate)


12.56÷3.14=4 3.14×﹙4÷2﹚²=12.56 12.56×6.28=78.8768